The present embodiments relate to ultrasound imaging. In particular, ultrasound imaging is used for feedback in high intensity focused ultrasound (HIFU).
HIFU is used to treat cancers, tumors, lesions, or other undesired tissue structures. Ultrasound energy heats the tissue sufficiently to necrotize the undesired tissue. The ultrasound energy is focused to avoid harming healthy tissue. Treatment with ultrasound may avoid invasive procedures, such as an operation or radio frequency ablation procedure.
Ultrasound imaging has been used to guide HIFU therapy. The imaging assists in focusing the therapy pulses on the undesired tissue. For example, a same array is used to image and transmit HIFU so that the HIFU is focused at the desired tissue. However, the HIFU may use a different array than used for imaging. Also, gas bubbles or cavitation during application of HIFU may result in inaccurate identification of the HIFU treatment region.
Attempts have also been made to monitor the thermal and biological changes of the tissue during these therapies. For example, ultrasound energy is used to measure thermal expansion coefficients (e.g., measure tissue expansion by speckle tracking), speed of sound in the tissue, or stiffness changes (e.g., strain imaging). However, these diagnostic based ultrasound tissue characterizations may not have sufficient signal-to-noise resolution or may not be clinically viable.